Cannot send to multiple email addresses within same contact

I am trying to send an Outlook email (through Write-Email) to contacts, some of whom have multiple email addresses. These are housed in the email fields supplied by ACT: Email and Email-2. When I select the contacts and do a Write-Email, it only addresses the Oulook email with the emails in the Email field, not the Email-2 field addresses as well.

Both fields (Email and Email2) are designated as email fields under Tools - Define Fields.